Abstract
We examined whether corticotropin-releasing factor (CRF) was involved in orexin-induced grooming and face-washing behaviors, and whether orexin was involved in the stress reaction. Administration of alpha-helical CRF, CRF antagonist, alone had no behavioral effect, but it blocked the orexin-induced grooming and face-washing behaviors in rats. The level of corticosterone increased in a dose-dependent manner 15 min after icv injection of orexin, and it remained high for at least 60 min. In 2-month-old rats, 1 h of immobilization stress increased orexin mRNA levels, but not the melanin-concentrating hormone (MCH) mRNA, in the lateral hypothalamic area (LHA). In 6-month-old rats, 30 min of cold stress increased the expression of orexin mRNA in the LHA. Unlike in the 2-month-old rats, immobilization stress did not change orexin mRNA expression in 6-month-old rats. These results suggest that CRF is involved in orexin-induced behaviors, and that orexin may play an important role in some stress reactions.
Copyright 2000 Academic Press.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Appetitive Behavior / drug effects*
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Carrier Proteins / biosynthesis
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Carrier Proteins / genetics
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Carrier Proteins / pharmacology*
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Cold Temperature
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Corticosterone / blood
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Corticotropin-Releasing Hormone / antagonists & inhibitors
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Corticotropin-Releasing Hormone / biosynthesis
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Corticotropin-Releasing Hormone / pharmacology*
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Hypothalamic Area, Lateral / metabolism*
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Hypothalamic Hormones / biosynthesis
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Immobilization
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Injections, Intraventricular
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Intracellular Signaling Peptides and Proteins*
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Male
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Melanins / biosynthesis
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Neuropeptides / biosynthesis
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Neuropeptides / genetics
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Neuropeptides / pharmacology*
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Orexins
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Pituitary Hormones / biosynthesis
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RNA, Messenger / analysis
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Rats
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Rats, Sprague-Dawley
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Rats, Wistar
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Stress, Physiological / metabolism*
Substances
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Carrier Proteins
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Hypothalamic Hormones
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Intracellular Signaling Peptides and Proteins
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Melanins
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Neuropeptides
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Orexins
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Pituitary Hormones
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RNA, Messenger
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melanin-concentrating hormone
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Corticotropin-Releasing Hormone
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Corticosterone